| Summary: | 碩士 === 國立成功大學 === 口腔醫學研究所 === 101 === Caries is one of the most popular oral diseases derived from acid challenge produced by cariogenic bacteria. Streptococcus mutans is the major pathogenic bacteria involved in caries, which can form dental plaque followed by demineralization of tooth mineral tissues. Not all bacteria in oral cavity contribute the development of caries. Instead, many oral bacteria have protective effect to caries development through counter-balance of the cariogenic flora. Therefore, it is important in the design of effective anti-carious strategy that integrates selectivity for cariogenic pathogens inhibition and non-cariogenic bacteria preservation. Hydroxyapatite, as the main mineral component of bones and teeth, has applications as biomaterials, tissue engineering, and drug delivery, etc. In previous study, organic molecules and polymers play an important role in the formation of these spherical hydroxyapatite particles through forming a specific structure of micelles in solution. However, a solution method to prepare fluoride-doped hydroxyapatite (Fluorapatite) with hierarchical structure via an ion-assisted and surfactant-free mineralization process has been employed. High-resolution thermal field emission scanning electron microscope (FE-SEM), X-ray diffraction and Fourier transform infrared spectroscope were used to characterize the derived particles. The fluoride release of fluorapatite particles was evaluated by fluoride ion electrode. The fluoride release concentration was higher in acidic environment than in neutral. Further, the antibacterial activity of the particles was evaluated in S. mutans and S. gordonii by colony forming unit assay. The results showed fluorapatite could not only selectively suppress cariogenic bacteria but protect the probiotics of the oral cavity. We also confirmed the differential antibacterial activity in an ex vivo model using human tooth enamel slab by FE-SEM. These nanoparticles provide a new concept to develop smart anti-caries strategy as the nanoparticles not only protect teeth against the threat of cariogenic bacteria but also protect the probiotics.
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